Apparatus and method for retorting of oil shale



June 20, 1961 w. s. DoRsEY 2,989,442

APPARATUS AND METHOD FOR RETORTING OF OIL SHALE Filed nec. e, 1958United States A Patent O APPARATUS AND METHOD FOR RETGRTING j OF OILSHALE l William Smith Dorsey, Fullerton, Calif., assign'or `to Union OilCompany of California, L'os Angeles, Calif., a corporation of CaliforniaY Filed Dec. 8, 1958, Ser. No. 779,014

' 13 Claims. (Cl. 202-'6) v. This invention relates generally to aprocess for heat treating of oil-containing or oil-producing solids toproduce hydrocarbon oils and gases therefrom. The invention particularlyis well adapted to the retorting of oil shale to produce shale oil andgas.

`An excellent process for shale oil production is that shown in thepatent to Berg, U.S. 2,501,153, in which combustion of carbonaceousresidue at a high zone within an inverted truste-conical chamber fedwith shale solids from/'the bottom produces combustion gas which movesdownward and educts shale oil and gases from raw shale at'a'lo'wer zone.The educted shale oil and gases are removed through openings in theunitary chamber just above the entry position of raw shale. since -boththe eduction step and the combustion step are ca rried on in the samechamber, it is difficult to vary the conditionsof the two stepsindependently. Thus the temperature, flow ra-te and composition of thecombustion gas'largely determine the conditions of the eduction. Aprocess in-'which the` two steps are carried out more independently isshown in` U.S. patent to Ogorzaly et al. 2,689,787. In this processhowever, it is essential that the spent shale produced in the eductionzone be pulverized beforev being subjected to combustion, sincethe'latter fis* carried out in the iluidized state. This is not onlyunnecessary, but makes it impossible to obtain the benelits vof movingbed combustion, such as smaller equipment, simpler control, highertemperature, etc.

It is, therefore, an object of the present invention 'to` provide animprovement of the above oil shale retorting processes, in bothexibili-ty and efficiency.

Briefly, the invention is carried out'in a process comprising asubstantially continuous upward feed of coarse oil-producing particlesof up to about six inches, preferably inthe size rangeof 1A: inch to 4inches, in a retort having a horizontally enlargingy area with increasein eleveation.' Produced gases, vapors and liquids along with eductionuid are removed just above the bottom entry location of the particles.An eduction gas mixture of controlled temperature not greater than about1500 F., a controlled composition, and of a volume suicient to maintainthe desired solids temperatures land the de-4 sired product gas, issupplied to the top of the eduction zone. Particles, having had, optimumoil quantity produced therefrom in the eduction chamber but containing acombustible carbonaceous residue, are transferred substantially-unbrokenin size front the top of the eduction chamber to the upper part of anadjacent combustion chamber having'downward and outward flared interiorsidewalls. The particles flow downward in a compact moving mass Athroughthe combustion chamber. Combustion supporting gas, such as air, isprovided tothe lower part of the Vcombustion chamber to burn thecarbonaceous residue and-tov produce hot combustion gas a't'atemperature vgreater than about 2100 F. This, when selectively mixedwith cooler recycle gas obtained from the bottom of the eduction zone,provides the desired eduction gas. Y

The process f the inventionv'villV bemore readily understood from Vthefollowing detailedn description and accompanying drawing showingapparatuswith aschematic represen-tation ofmaterial ow forV practice ofthe process. l

In this process,

ice

Referring to the figure, rich coarsely crushed oil shale, preferably allof which is one-fourth to 4 inches in size and not greater than sixinches in size, is introduced from crushers into shale hopper 1 and isthen passed down through a hopper oil liquid level 2 to a convention-alupward forcing solids feeding apparatus rcontained in feeder case 3. Thefeeder apparatus in feeder case 3 may take the form of that shown inBerg, U.S. 2,501,153, or it may be of the form substantially asrepresented in which tilt controlling hydraulic cylinder 4 and verticalfeeding hydraulic cylinder 5 have respective pistons operated'. thereinin properly timed sequence so as to take on a shale charge at hopper 1and then position vertically to force raw shale upward through verticalthroat 6. Large cylinder 7 holds the fed shale charge supported on largefeeder piston 8 therein. The shale solids comprise a minimum of smallersize particles. The larger size particles remain preferably as unchangedas is possible in exterior physical size and conliguration throughoutthe retortingl process. Shale Vmoves upward through throat 6 and throughfrusto-conical section 9 which is surrounded by an outer chamber 10shown in cut-away section. PromV section 9 shale moves upward into andthrough eduction. chamber 11, having the form of an inverted conicalsection. Spent shale is removed at the top of eduction.

Y chamber 11 by means as will be hereinafter explained.

Hot eduction gas, preferably at about l050 F. ,toV 1250 F., and lessthan about 1500 F. maximum temperature, represented by the arrow 12,passes downward intoV and through the counter-current upward iow ofshale. Shale in the eduction zone preferably need not. exceed 970 F.when contacted by the hot gas. These lower temperatures substantiallylimit carbonate decom-- position while still providing completeeduction.

The eduction gas 12 is generally effectively supplied atA a supericialmass velocity of Y135 to 535 pounds each hour per square foot of bedcross section at the surface of the eduction zone for oil shales havinga Fischerassay range of about 70` gallons per ton to as low as 25gallons per ton. The shale which has been previously heated torationsection. v

Outer chamber 10, which receives the volatile hydrocarbons through thetop of slots 14 and which receivesv the liquid oil through the bottom ofthe slots 14, may be` designated a separation chamber from which gasproduct is removed through line 16 and oil product is removed throughline y18, respectively, above and below a con?.

trolled liquid level20 in chamber 10. For simplicity: of illustration,gas blower means, liquid oil pumping means: and controlling means forproduct removal are not shown,

as conventional apparatus may be used and such formj product llines bymeans of lines 22 and 23, respectively.,

Oil product passes oft through 1ine24 to storage facilitiesf;

not shown, A substantial portion of ,gas Pr0ductisre` cycled portion ofproduct gas can be preheated prior to mixing with the combustion gasesby closing normally open valve 70, opening normally closed valve 72, andconducting the recycled portion of product gas` through line 74,preheater 76 and line 78 into -hood enclosure 28. A lesser portion ofproduct gas is taken off at line 32 which it is necessary to remove dueto normal gas formation in the system and to combustion gas additionsthereto, as will be shown.

Solids 34 at the top of the eduction chamber 9 are pushed off thecentral area of the rising solids mass by a scraper blade 36 which isdriven by electric motors, or the like, mechanically connected toattachment means such as 38 at the ends of the scraper. The scraperblade 36 may be operated to tip out of engagement with the solids 34when returning in the reverse direction to the original scrapingposition shown. 'Ihe solids 34 collected by the scraper are removed bygravity by way of a surrounding spillway 40 which transfers the solidsto a central area of a combustion chamber 42. The spillway 40 may, ifdesired, have an upper terminus which commences 180 degrees around theeduction chamber with respect to the central area of its lower terminusso that scraper apparatus may be constructed to scrape in bothdirections. The scraper blade 36 preferably has a slope such that, withits forward movement during scraping, solids 34 are forced forward andslightly upward which minimizes agitation of solids on the bed surfaceby way of rolling and abrading against one another. Preferably thescraper blade 36 moves in a constant direction path rather than along acurved or a partially curved path. It is also preferred that scrapingmeans moves with a straight thrust rather than with a rotary sweepertype action. The preferred movement of the scraper recited aboveprovides for a minimum of particle agitation in comparison to the moreinvolved diverse scraping movements. It is apparent that variouslymodified scraper blades and shallow scoop devices may also provide suchminimal agitation movement of shale particles.

The combustion chamber 42 has interior sidewalls which are outward sothat solids 44, substantially unbroken in size from the eductionchamber, may settle downward to be ejected from the bottom of thecombustion zone by mechanically moved supporting grates 46. Thecombustion chamber may be lined with heatwithstanding refractory brick,or may be constructed as shown of heat-withstanding and corrosion-proofmetal. The combustion chamber 42 preferably has a solely roundedconguration in cross-section, either a circular or an oval shape beingmost suitable, so as to minimize edge resistances to downward movementof hot solids. Sufficient height is provided the combustion chamber togive it a hot combustion bed volume adequate to burn all, or as much asdesired, of the carbonaceous deposits which are left on the shale solids34 at the top of the eduction chamber. The burning takes place with theaid of a controlled volume of air which enters hopper 50 below Ithegrates 46 through one or more lines 48. Air volume is carefullycontrolled so that no excess of oxygen is available in the combustiongas 52 which moves upward from the burning coarse particles of solids44. If desired, the recycle gas 26 from the bottom of the eductionchamber may be pre-heated, prior to entry into hood 28, to aytemperature within the range of about 500 F. to about 1,000 F. byindirect contact with these hot combustion gases, or with part of them,such as the gases withdrawn through line 54 or those that are passedthrough damper 56, or 1by indirect contact with hot shale ash. With suchan arrangement, a lesser amount of combustion gas 52 is required toobtain suticient eduction gas 12 with adequate heat content than in theinstance where the recycle gas 26 is not pre-heated.

As an alternative to burning the carbonaceous shale, or in combinationtherewith, steam may also be introduced into hopper 50, as for examplethrough line 48, with or without air, to give a water-gas reaction withthe not carbon residues on solids in chamber 42. The gases produced inthe Water-gas reaction of steam and carbon may then form a part of theeduction gas 12. The burning of carbonaceous solid residue on the shalein combustion chamber 42 takes place at upwards of 2l00 F. which gives ahigh temperature combustion gas. Combustion gas is drawn olf incontrolled amounts through line 54 i exiting from within the chamberbelow a pivoted damper 56. Damper 56 is designed, as shown along a pivotView, to substantially block passage of gas between the combustionchamber and eduction chamber, if desired, while still admitting shalesolids from the spillway 40. Damper 56 may be rotated by externalcontrol counterclockwise, as viewed, so as to admit controlled amountsof combustion gas 58 on either side of its pivot, which gas then mixeswith the recycled product gas 30 to form the controlled volume andtemperature eduction gas 12.

Shale ash 60 collected in hopper 50 is removed by a star feeder 62 andis then carried away by a belt conveyor 64 to a refuse pile. Combustiongas 54 removed from the system is also at a temperature of about 2100F., or above, and may be used to preheat recycle gas as described above,or sent to waste heat boilers for the production of auxiliary power, orthe like.

The burning of carbonaceous solid residue on relatively unbroken coarseparticles of solids 44 provides not only a combustion bed which isrelatively open and having a greater over-all average density than afluidized bed, but also a combustion gas substantially free of ne solidsin the form of finely divided fly ash, such as is produced by aIlluidized bed.

The foregoing process provides for high oil yield at a low temperatureeduction which is very exactly controlled by the temperature modifyinghot combustion gas added to the recycle eduction gas between thecombustion zone and the eduction zone. The eduction gas contains noexcess free-oxygen with which the educted oil can combine chemically toreduce oil quality. Eduction gas is primarily made up of recycle gaswhich is natural and compatible with the eduction zone since it isproduced there as well. Combustion of carbonaceous shale residues takesplace in a separate combustion zone which permits easier generation ofhot modifying combustion gas without risk of oxygen contamination of theeduction zone oil. The combustion is accomplished on solids ofsubstantially unbroken coarse particle size producing an openuncompacted bed with little or no production of line solids in thecombustion gas. A speciiic example of the process as applied to Coloradooil shale is shown in the following tabulated data:

Eduction chamber solids entry 5.5 ft. diameter.

Eduction chamber solids exit-- 17 ft. diameter. Eduction chamber height(total including product separation slot area) 25 ft. Solids feed rate1000 tons (dry weight) per day. Solids size range |8 mesh to -6 inches.Shale solids (Fischer assay) 35 gal. per ton. Oil recovery RA.Combustion gas temperature 2100+ F. Recycle gas temperature F. Eductiongas temperature 1050 to 1250* F. Gravity of recovered oil 22 API.Eduction gas volume 1600 ft.s per ton shale (dry weight). Combustionchamber: 1

Combustion chamber top cross-section 240 ft?. Combustion chamber bottomcross-section 270 ft?. Combustion chamber solids bed height. 9ft.

Total combustion l gas Y produced 700 ft.3 per ton shale Less than V2inch 5%. Vz-Z inches 45%. 2-4 inches 45%. 4-6 inches 5%.

1Optional combustion chamber dimensions:

Top cross-section-190 to 300 ft2. Bottom cross-section-21O to 350 ft.sends Y1aed height- 1 to 15 ft.

Advantages of the invention resulting from a separate combustion zone inthe foregoing process for eduction of nonuidized oil shale includes theopportunity to more exactly determine and control optimum conditions ofeduction as indicated by resulting oil yield. The eduction zone isseparate and may therefore have its conditions such as eduction fluidvolume, temperature, and the like, selectively maintained for bestresults rather than as dictated by the requirements of the process stepof another zone, such as for generation of an eduction uid. Advantage ofthe invention over a fluidized process includes reduced equipment sizeper unit of oil shale processed. Such reduced equipment size resultsfrom the fact that fluidization of particles generally includes somemeans of expansion of the overall volume occupied by oil shale particlesso as to insure elective contact of `all particles with the fluidizedprocess conditions.

Although the above specification and specific example in the tabulateddata indicate the preferred apparatus and mode of practice comprisingthe invention, it is to be understood that others skilled in the art maydevise modifications still within the spirit and scope of the expresslimit-ations included in the following claims which define theinvention.

I claim:

l. An apparatus adapted for the continuous eduction of shale oil and theindependent combustion of spent shale to furnish ho-t gases for saideduction which comprises: a vertically disposed eduction chamber whichincreases in cross-section with increase in elevation, said eductionchamber having means in its lower peripheral sidewall for removal ofliuids without substantial removal of solids, means for passing asubstantially compact moving bed of said oil shale particles upwardlythrough said eduction chamber, a vertically disposed combustion charnberhaving a `construction such as to increase in cross. section Withdecrease in elevation, said combustion chamber being disposed lateralyfrom and below the top of said eduction chamber, means for transfer ofupwardly fed oil shale particle solids from the top of said eductionchamber to said combustion chamber with a minimum of agitation, meansfor withdrawing solids from the lower part of said combustion chamber soas yto maintain a compact bed of substantially uniformly flowingparticles therein, means for introducing oxygen-containing gas at thebottom of said combustion chamber substantially uniformly across itscross-section, means for removing a first stream of hot combustion gasesfrom the top of the combustion chamber, means for transferring a secondstream of combustion gases to said eduction chamber top, means forseparating a portion of gaseous product removed from said eductionchamber, and means for mixing said portion of gaseous product with saidsecond stream of hot combustion gases and passing the mixture into thetop of said eduction chamber.

2. Apparatus as defined in claim l wherein said means for transferringsaid second stream of combustion gases to said eduction chamber topcomprises: -a pivoted damper means and a surrounding hood disposed overboth said eduction chamber top and said combustion chamber top,

6 said damper means having 'an arranged relationship with' the interiorof said hood and with solid particle flow entering said combustionchamber so as to selectively limit volume passage of said second streamof com-1 bustion gases with the pivoted rotational position of saidldamper. A' Y l Y l3. Apparatus as defined in claim 1 wherein said meansfor transfer of oil shale particles from eduction chamber toVcombustionV chamber comprises a spillway with a gravity feed and ascraper blade for minimal agitating movement lof oil-educted particlesfrom the top ofsaid eduction chamber to said spillway'which is directedto said combustion chamber top. 4. Apparatus as defined in claim 3wherein said scraper blade slopes in the direction of its movement ina'maxmer` so'asto provide an upward lift to solids particles whilemoving saidsolids particles.' Y l 5. In a continuous shale-retortingprocess wherein a moving compact bed of shale is rst subjected tohot gaseduction to generate oil, and the carbonaceous residue is then burned togenerate gas for said eduction, the improved method for maintainingindependent control over said eduction and burning steps, whichcomprises passing raw shale particles of Varying sizes up to about sixinches diameter upwardly as a substantially compact bed through aneduction zone, passing a hot eduction uid downwardly through saideduction zone to contact said particles and educt liquid and gaseoushydrocarbons therefrom leaving educted carbonaceous particles,withdrawing liquid and gaseous products from the lower portion of saideduction zone, moving said educted carbonaceous particles from Itheupper surface of said eduction zone to the upper level of a combustionzone without substantial comminution thereof, said combustion zone beingdisposed laterally from and below the top of said eduction zone, passingsaid educted particles downwardly through said combustion zone in theform of a compact bed of substantially uniformly owing particles,introducing oxygen-containing gas upwardly through said combustion zonefor supporting combustion of carbonaceous particles to produce a hotcombustion gas and mixing at least part of said hot combustion gas withat least part of the gaseous product removed from the lower portion ofsaid eduction zone to form said hot eduction uid.

6. A continuous method of retorting carbonaceous solids as defined inclaim 5 wherein said gas removed from `said eduction zone is preheatedprior to being mixed with said combustion gas.

7. A method according to claim 5 in which steam is also introduced intosaid combustion zone to react with part of said carbonaceous residue toform carbon monoxide and hydrogen.

8. In a continuous shale-retorting process wherein a moving compact bedof shale is tirst subjected to hot gas eduction to generate oil, and thecarbonaceous residue is then burned to generate gas for said eduction,the improved method for maintaining independent control over saideduction and burning steps, which comprises passing raw shale particlesof varying sizes of less than about six inches diameter upwardly into anupwardly enlarging eduction zone in countercurrent contact with a hoteduction fluid, moving substantially unbroken liuid educted carbonaceousparticles from the upper surface of said eduction zone to the upperlevel of an adjacent but laterally removed combustion zone by way of aspill zone having gravity effected movement therethrough moving saidcarbonaceous particles downwardly as a compact bed in said combustionzone, providing oxygencontaining gas to the bottom of said combustionzone so as to burn carbonaceous material on said particles at a minimumtemperature of about 2l00 F., removing burned particles from the bottomof said combustion zone, removing hot combustion gas from the top ofsaid combustion zone, removing liquid oil and product gas from saideduction zone at the bottom thereof, mixing a portion of said hotcombustion gas with a portion of said product gas to form a gas mixturehaving a temperature between about 1050 F. and about 1500 F., andpassing said mixture into the top of said eduction zone to act as saideduction fluid.

9. A method as defined in claim 8 wherein said solids range from 1A to 4inches in size.

10. A method as dened in claim 8 wherein said combustion zone increasesin cross-section at successively lower elevations.

11. A method as dened in claim 8 wherein said gas mixture passed to thetop of said eduction zone is at a temperature of about 1050 F. to 1250F. and said solid particles are maintained at about a temperature of 970F. for the hottest of said upwardly moving solids.

12. A method as defined in claim 8 wherein said oil shale containsearbonates and the solid particles are re- 8 torted at temperatureswhich substantially avoid carbonate decomposition in said eduction zone,and wherein said combustion gas is produced in said combustion zone attemperatures high enough to decompose carbonates extensively therein.

13. A method as defined in claim 8 wherein said gas mixture passed tothe top of said eduction zone is provided thereto at a rate of about 135to 535 pounds each hour per square foot of eduction zone top surface foroil shales having a Fischer assay range of about 70 gallons per ton toas low as 25 gallons per ton.

References Cited in the le of this patent UNITED STATES PATENTS2,640,014 Berg May 26, 1953 2,661,327 Dalin Dec. 1, 1953 2,689,787Ogorzaly et al. Sept. 21, 1954

1. AN APPARATUS ADAPTED FOR THE CONTINUOUS EDUCTION OF SHALE OIL AND THEINDEPENDENT COMBUSTION OF SPENT SHALE TO FURNISH HOT GASES FOR SAIDEDUCTION WHICH COMPRISES: A VERTICALLY DISPOSED EDUCTION CHAMBER WHICHINCREASES IN CROSS-SECTION WITH INCREASE IN ELEVATION, SAID EDUCTIONCHAMBER HAVING MEANS IN ITS LOWER PERIPHERAL SIDEWALL FOR REMOVAL OFFLUIDS WITHOUT SUBSTANTIAL REMOVAL OF SOLIDS, MEANS FOR PASSING ASUBSTANTIALLY COMPACT MOVING BED OF SAID OIL SHALE PARTICLES UPWARDLYTHROUGH SAID EDUCTION CHAMBER, A VERTICALLY DISPOSED COMBUSTION CHAMBERHAVING A CONSTRUCTION SUCH AS TO INCREASE IN CROSSSECTION WITH DECREASEIN ELEVATION, SAID COMBUSTION CHAMBER BEING DISPOSED LATERALY FROM ANDBELOW THE TOP OF SAID EDUCTION CHAMBER, MEANS FOR TRANSFER OF UPWARDLYFED OIL SHALE PARTICLE SOLIDS FROM THE TOP OF SAID EDUCTION CHAMBER TOSAID COMBUSTION CHAMBER WITH A MINIMUM OF AGITATION, MEANS FORWITHDRAWING SOLIDS FROM THE LOWER PART OF SAID COMBUSTION CHAMBER SO ASTO MAINTAIN A COMPACT BED OF SUBSTANTIALLY UNIFORMLY FLOWING PARTICLESTHEREIN, MEANS FOR INTRODUCING OXYGEN-CONTAINING GAS AT THE BOTTOM OFSAID COMBUSTION CHAMBER SUBSTANTIALLY UNIFORMLY ACROSS ITSCROSS-SECTION, MEANS FOR REMOVING A FIRST STREAM OF HOT COMBUSTION GASESFROM THE TOP OF THE COMBUSTION CHAMBER, MEANS FOR TRANSFERRING A SECONDSTREAM OF COMBUSTION GASES TO SAID EDUCTION CHAMBER TOP, MEANS FORSEPARATING A PORTION OF GASEOUS PRODUCT REMOVED FROM SAID EDUCTIONCHAMBER, AND MEANS FOR MIXING SAID PORTION OF GASEOUS PRODUCT WITH SAIDSECOND STREAM OF HOT COMBUSTION GASES AND PASSING THE MIXTURE INTO THETOP OF SAID EDUCTION CHAMBER.
 5. IN A CONTINUOUS SHALE-RETORTING PROCESSWHEREIN A MOVING COMPACT BED OF SHALE IS FIRST SUBJECTED TO HOT GASEDUCTION TO GENERATE OIL, AND THE CARBONACEOUS RESIDUE IS THEN BURNED TOGENERATE GAS FOR SAID EDUCTION, THE IMPROVED METHOD FOR MAINTAININGINDEPENDENT CONTROL OVER SAID EDUCTION AND BURNING STEPS, WHICHCOMPRISES PASSING RAW SHALE PARTICLES OF VARYING SIZES UP TO ABOUT SIXINCHES DIAMETER UPWARDLY AS A SUBSTANTIALLY COMPACT BED THROUGH ANEDUCTION ZONE, PASSING A HOT EDUCTION FLUID DOWNWARDLY THROUGH SAIDEDUCTION ZONE TO CONTACT SAID PARTICLES AND EDUCT LIQUID AND GASEOUSHYDROCARBONS THEREFROM LEAVING EDUCTED CARBONACEOUS PARTICLES,WITHDRAWING LIQUID AND GASEOUS PRODUCTS FROM THE LOWER PORTION OF SAIDEDUCTION ZONE, MOVING SAID EDUCTED CARBONACEOUS PARTICLES FROM THE UPPERSURFACE OF SAID EDUCTION ZONE TO THE UPPER LEVEL OF A COMBUSTION ZONEWITHOUT SUBSTANTIAL COMMINUTION THEREOF, SAID COMBUSTION ZONE BEINGDISPOSED LATERALLY FROM AND BELOW THE TOP OF SAID EDUCTION ZONE, PASSINGSAID EDUCTED PARTICLES DOWNWARDLY THROUGH SAID COMBUSTION ZONE IN THEFORM OF A COMPACT BED OF SUBSTANTIALLY UNIFORMLY FLOWING PARTICLES,INTRODUCING OXYGEN-CONTAINING GAS UPWARDLY THROUGH SAID COMBUSTION ZONEFOR SUPPORTING COMBUSTION OF CARBONACEOUS PARTICLES TO PRODUCE A HOTCOMBUSTION GAS AND MIXING AT LEAST PART OF SAID HOT COMBUSTION GAS WITHAT LEAST PART OF THE GASEOUS PRODUCT REMOVED FROM THE LOWER PORTION OFSAID EDUCTION ZONE TO FORM SAID HOT EDUCTION FLUID.